Preheat oven to 160C or 325F. Prepare a 7 inch tube pan.
Combine egg yolks and brown sugar in a bowl and mix well. Whisk in water and oil. Stir in flour then the kinko. Set aside.
Mix the sugar and corn flour together in a bowl. Whisk the egg whites until foamy. Add half of the flour-sugar mixture and continue beating for a few minutes. Add the remaining flour-sugar mixture and beat until egg whites are stiff.
Add 1/3 of the meringue into the egg yolk mixture and fold in lightly. Add the remaining meringue and fold to incorporate completely.
Pour batter into pan and bake for 40 to 50 minutes. When the cake is done, remove from oven and invert pan onto a cooling rack. Cool completely before slicing.
Kinako Cream Filling and Decoration
Combine the cream, kinako and honey in a bowl and whip until cream reaches medium-stiff peaks. Scrape cream into a piping bag fitted with a star tip.
Assemble the cake sandwiches: Slice the cooled cake into 10 to 12 portions depending on how thick you like your slice of cake to be. It's usually better to have thicker slices of cake as they're less likely to fall over under the weight of the cream and bananas. Make a slit slightly more than halfway down the center of each slice. Pipe in the cream and top with the sliced bananas. Serve immediately or if not, store in the fridge.